diff --git a/deel/torchlip/functional.py b/deel/torchlip/functional.py
index 5a362da..9143cdf 100644
--- a/deel/torchlip/functional.py
+++ b/deel/torchlip/functional.py
@@ -212,7 +212,9 @@ def max_min(input: torch.Tensor, dim: Optional[int] = None) -> torch.Tensor:
     return torch.cat((F.relu(input), F.relu(-input)), dim=dim)
 
 
-def group_sort(input: torch.Tensor, group_size: Optional[int] = None, dim : int = 1) -> torch.Tensor:
+def group_sort(
+    input: torch.Tensor, group_size: Optional[int] = None, dim: int = 1
+) -> torch.Tensor:
     r"""
     Applies GroupSort activation on the given tensor.
 
@@ -220,21 +222,28 @@ def group_sort(input: torch.Tensor, group_size: Optional[int] = None, dim : int
         :py:func:`group_sort_2`
         :py:func:`full_sort`
     """
-    
+
     if group_size is None or group_size > input.shape[dim]:
         group_size = input.shape[dim]
 
     if input.shape[dim] % group_size != 0:
         raise ValueError("The input size must be a multiple of the group size.")
 
-    new_shape = input.shape[:dim]+(input.shape[dim]//group_size,group_size)+input.shape[dim+1:]
+    new_shape = (
+        input.shape[:dim]
+        + (input.shape[dim] // group_size, group_size)
+        + input.shape[dim + 1 :]
+    )
     if group_size == 2:
         resh_input = input.view(new_shape)
-        a, b = torch.min(resh_input, dim+1,keepdim=True)[0], torch.max(resh_input, dim+1,keepdim=True)[0]
-        return torch.cat([a, b], dim=dim+1).view(input.shape)
+        a, b = (
+            torch.min(resh_input, dim + 1, keepdim=True)[0],
+            torch.max(resh_input, dim + 1, keepdim=True)[0],
+        )
+        return torch.cat([a, b], dim=dim + 1).view(input.shape)
     fv = input.reshape(new_shape)
 
-    return torch.sort(fv,dim=dim+1)[0].reshape(input.shape)
+    return torch.sort(fv, dim=dim + 1)[0].reshape(input.shape)
 
 
 def group_sort_2(input: torch.Tensor) -> torch.Tensor:
diff --git a/tests/test_activations.py b/tests/test_activations.py
index 568e053..309fe28 100644
--- a/tests/test_activations.py
+++ b/tests/test_activations.py
@@ -131,7 +131,7 @@ def test_GroupSort(group_size, img, expected):
         xnp = np.repeat(
             np.expand_dims(np.repeat(np.expand_dims(xn, -1), 28, -1), -1), 28, -1
         )
-        xnp = uft.to_NCHW_inv(xnp) # move channel if needed (TF)
+        xnp = uft.to_NCHW_inv(xnp)  # move channel if needed (TF)
         x = uft.to_tensor(xnp)
         uft.build_layer(gs, (28, 28, 4))
     y = gs(x).numpy()
@@ -141,11 +141,12 @@ def test_GroupSort(group_size, img, expected):
         y_t = np.repeat(
             np.expand_dims(np.repeat(np.expand_dims(y_tnp, -1), 28, -1), -1), 28, -1
         )
-        y_t = uft.to_NCHW_inv(y_t) # move channel if needed (TF)
+        y_t = uft.to_NCHW_inv(y_t)  # move channel if needed (TF)
     # print("aaa",y_t.shape, y_t)
     # print("aaab",y.shape, y)
     np.testing.assert_equal(y, y_t)
 
+
 @pytest.mark.parametrize("group_size", [2, 4])
 def test_GroupSort_idempotence(group_size):
     gs = uft.get_instance_framework(GroupSort, {"group_size": group_size})
diff --git a/tests/test_unconstrained_layers.py b/tests/test_unconstrained_layers.py
index 69b829d..f5834c3 100644
--- a/tests/test_unconstrained_layers.py
+++ b/tests/test_unconstrained_layers.py
@@ -37,8 +37,8 @@
 
 def compare(x, x_ref, index_x=[], index_x_ref=[]):
     """Compare a tensor and its padded version, based on index_x and ref."""
-    x = uft.to_numpy(uft.to_NCHW(x))
-    x_ref = uft.to_numpy(uft.to_NCHW(x_ref))
+    x = uft.to_NCHW(uft.to_numpy(x))
+    x_ref = uft.to_NCHW(uft.to_numpy(x_ref))
     x_cropped = x[:, :, index_x[0] : index_x[1], index_x[3] : index_x[4]][
         :, :, :: index_x[2], :: index_x[5]
     ]
diff --git a/tests/utils_framework.py b/tests/utils_framework.py
index cc33ebd..3107b06 100644
--- a/tests/utils_framework.py
+++ b/tests/utils_framework.py
@@ -527,9 +527,11 @@ def to_framework_channel(x):
 def to_NCHW(x):
     return x
 
+
 def to_NCHW_inv(x):
     return x
 
+
 def get_NCHW(x):
     return (x.shape[0], x.shape[1], x.shape[2], x.shape[3])